Hi, I have Saphire Radeon 7850 1GB and VG248QE. You have to use a DVI cable to get 144hz (I think DisplayPort also supports this but can't confirm it), HDMI won't let you go over 60Hz. The display is awesome, i upgraded from a 19" 60Hz Samsung S19B150 and I love the difference. Enjoy it.
Edit: Lol i just realized this is an 8 months old post. sorry for late answer